586 A MANUAL OF BACTERIOLOGY 



Endolimax nana is a small amoeba 6 ju-12 p. in diameter, which 

 is quite common in the intestine (Plate XXIII, g and h). Its 

 primary habitat may be the small intestine. Movement is slug- 

 gish, and the cytoplasm contains many food vacuoles filled with 

 bacteria. The nucleus is vesicular and contains a large karyosome. 

 Encystation occurs ; the cysts are ovoid and ultimately contain 

 four nuclei. 



lodamceba Biltschlii (Iodine cysts of Wenyon). An amoeba met 

 with in the intestine. Its diameter is usually 9/^-13 /A. The 

 cysts are of variable shape and characterised by the presence of 

 large round or ovoid bodies which stain intensely with iodine and 

 are probably composed of glycogen. 



Entamceba gingivalis. A small amoeba ( 10 /z-20 /*) which occurs 

 in the mouth, particularly in connection with pyorrhoea (see also 

 under '" Pyorrhoea "). 



These three forms are considered by Dobell to be non-pathogenic 

 and they cannot be cultivated. 



Free living (Umax forms) amoebae occasionally occur in the 

 bowel, and are the forms which have been cultivated. They will 

 frequently grow on agar in the presence of bacteria. 



Clinical Diagnosis 



1. Intestinal Protozoa are best examined in the fresh and living 

 condition and as soon after leaving the body as possible : the 

 encysted forms, however, do not alter for days after they have 

 been passed. 



A thin suspension of the faeces should be made with saline 

 solution and several thin preparations examined. A warm stage 

 should be used if it be desired to observe amoeboid movement 

 of amoebae or motility of flagellates. It may be difficult to 

 distinguish amoebae unless amoeboid movement is observed, and 

 for this purpose the stool should be quite fresh, free from urine, 

 and collected in a warmed bed-pan. In order to render the 

 nucleation of the cysts more evident the faeces may be rubbed 

 up into a thin suspension with a drop of Weigert's iodine solution 

 on a slide. A preliminary examination of the preparation may be 

 made with a -in. or i-in. objective with a high eye-piece, and 

 subsequently a more critical examination with the ^-in. oil 

 immersion objective. A micrometer eye-piece, by which exact 



